Upregulation of miR-132 attenuates osteoblast differentiation of UC-MSCs.

OBJECTIVE: Wnt/β-catenin signaling pathway plays a role in upregulating expression of osteoblast (OB) specific transcriptional factor Osterix and promoting OB differentiation. It was shown that the elevation of the miR-132 level was associated with sclerotizing inhibition. Bioinformatics analysis revealed the complementary binding site between miR-132 and 3'-UTR of β-catenin. This study investigated the influence of miR-214 in regulating β-catenin expression and differentiation of umbilical cord mesenchymal stem cells (UC-MSCs) into OB.
MATERIALS AND METHODS: UC-MSCs were induced to differentiate to OB. The expressions of miR-132, β-catenin, Osterix, and ALP, together with ALP activity were detected on day 0, 5, 10, and 15. The regulatory relationship between miR-132 and β-catenin was confirmed by dual luciferase reporter gene assay. UC-MSCs were divided into five groups, including agomir-control, miR-132 agomir, pGPH1-NC, pGPH1-β-catenin, and miR-132 agomir + pGPH1-β-catenin groups. β-catenin, Osterix, and ALP expressions, together with ALP activity were tested after induction for 15 days.
RESULTS: MiR-132 was downregulated, while β-catenin Osterix and ALP expressions, together with ALP activity were enhanced in the process of UC-MSCs differentiating into OBs. MiR-132 agomir and/or pGPH1-β-catenin transfection significantly reduced β-catenin expression, downregulated Wnt/β-catenin signaling pathway activity, declined Osterix level, weakened ALP expression and activity, and attenuated OB differentiation of UC-MSCs.
CONCLUSIONS: The level of β-catenin was enhanced, while the miR-132 level was decreased in the process of UC-MSCs differentiating into OBs. Upregulation of miR-132 inhibited the differentiation of UC-MSCs through suppressing β-catenin expression, attenuating Wnt/β-catenin signaling pathway activity, and downregulating Osterix level.